I've discovered 2 ways to kill people on the BWD elevator during corpseruns:
Priest: Stand at the edge on the upper level and face the entrance. Then, when the elevator is going down, Leap of Faith someone who is running towards you. Unless they stop pressing W while they're being pulled, they will fall to their death!
Paladin: Use hand of protection on someone waiting for the elevator to come up. If they jump, cancel HoP with another hand spell while they are still in range and watch as they die hilariously xD
If you know more ways to abuse people in BWD elevator, or in any other Cata frogger boss, please do share!